This invention relates to an aperture cover, such as a window shade, that adjusts light coming through a window in a building and functions as an electromagnetic shield.
Recently, office automation has become highly sophisticated. For example, communication equipment in offices use radio wave. To prevent radio noise from leaking into and out of the offices, an electromagnetic shield is required. A prior-art window blind that was proposed in the Japan Published Unexamined Patent Application No. S62-112889 effectively regulates light through a window and functions as the electromagnetic shield for an "intelligent building". In the prior-art window blind, slats connect to each other through transparent films, and electromagnetic shielding material is used for the slats and the transparent films.
However, since the prior-art window blind has clearance between the window frame and the blind and between the slats and the transparent films, electromagnetic energy is not sufficiently shielded. Radio waves easily leak into and out of the building, causing malfunctions of automated office equipment in the building.